I'm having a bit of an issue here. I have a linked list where each node contains a pointer to a string (which has been malloc'd when the node was created and inserted) and a pointer to the next node in the linked list.
I'm creating a function which will free the node (or effectively delete it). However, I'm receiving a free(): invalid pointer error.
I was having problems changing the value of my head node I passed it as an argument as head which would be the address. The parameter was defined as struct node *head. like this
I tried manipultaing pointer values to change head node value but it did not work. I saw some code online which used pointer to pointers(in code below) to change head node value it worked I dont fully understand why. Would like better understanding of why.
Would also like to know why the argument call needed &head instead of just head.
remove = deleteNode(&head,found); opposed to remove = deleteNode(head,found);
I am having issues freeing memory that I allocated when adding a node to a doubly linked list. I have tried adding free() at the end of the remove function from the list with no luck. I have tried using all sorts of temporary nodes and dummy nodes to free without losing node information. Have tried storing current node, moving to next one, then freeing the old current one, without luck. Everytime I try to free a node it destroys the list. It loses important node information and can no longer operate properly and I am met with all sorts of memory crashes. I will post my add and delete nodes functions here:
/** * Adds a node to a given list * * @param q pointer a a list * @param node pointer to the node to be added */ void list_add(list *q, path *node){ path *pn; if(!(pn = (path*)malloc(sizeof(*pn)))){ perror("malloc"); exit(1);
[Code] ....
Those free's at the end are to get rid of nodes I malloced in find_path. This find_path works really well when run once lol. It finds shortest path and prints it no problem, but doing it over and over again will be problematic as it is leaking almost every bit of memory it uses />.
So in short, how to free an allocated node when I remove it from a list while still being able to use it? I have tried moving the remove function to different locations like the end of the file and still no luck. I even tried allocating a new current_node each iteration of while loop, using it, then freeing it at the end of the while loop and took out the allocation in the list_add() function. This didn't work either />. How to stop the leakage.
I've been working on this program and am finished with what I want it to accomplish. But the last step I'd like to take is to delete the linked list and free all the memory. When I free the memory the way I am right now, the program breaks. I'm not sure how I should go about freeing and setting things to NULL.
I create A program that will Add and Display the Link List but I have problem on it. If I add it will inserted in the prev node not in the next node. Here's my source code.
#include <stdio.h> typedef struct Member { int id; char name[256]; struct Member *next;
I have a struct with some select student information. My wish is to be able to have the user type in a surname from the list, and for that entry to be deleted. However I am slipping up for some reason.
Here is the start of my program showing my struct:
This is what I have at the moment which works as I would like but wondering if there is a better way of handling? Currently just making sure I know linked-lists well enough.
I'm trying to impliment a simple singly linked list, then allow a user to add a new node. I have mocked up a siimple example to illustrate my point using Linked Lists...
So I have done things similatr to this in C# and Java but not in C. There maybe some parts of this I'm sure some will disagree with in terms of buffers,overflow etc. but it's just the linked list part that I am interested in at the moment, I am only doing it like this because when it works, I will be extracting the working linked list stuff into another program that can deal with its I/O etc.
I have tried to comment as best I can to demonstarte my intentions and understandings per line of code. The add function needs to add a node of value x that the user has input, and add that to the end of the list - I'm sure that the print function is not doing all its supposed to do...
If p is a pointer pointing a node to be deleted, then what's wrong in the following code:
cout << "Do you want to delete this record? (y/n) "; if (getch() == 'y' || getch() == 'Y'){// Delete record. if (p == *ph){//If first node is to be deleted. *ph = (*ph)->next; delete p;
I have to write a program which has the user be able to enter a specific value at a specific position of the linkedlist, replacing that node with the user defined value
EX: Enter the value 5 at 2nd node, which will override the old value at the 2nd node with the new one
I am getting a compiler error which terminates my program right after the user presses the return key after he/she has given a position to change the value
Error: Unhandled exception at 0x013C50C1 in Linked(1).exe: 0xC0000005: Access violation reading location 0x0000812B.
I am not going to show the whole code as the problem resides solely on the insert function:
void TheNode::insert(double num, int choice) { int post = 0; MyNode *ptr = new MyNode; (*ptr).value = num; MyNode *previous = head; MyNode *current = head->next;
Still toying with my self-coded linked list class and now another question: should I delete each node of my class with the delete in the class destructor or is it done automatically when the main() function ends?
How to remove node from linked list. I am trying to implement this in a file record to remove data from struct..I dont know how addressing in linked list work for structs;
Now, when I iterate back through my list (I want to start at the tail and work my way towards the head), I can only ever get the 1st node to print, then the 2nd node is garbage, which means, to me, that I've linked something wrong.
While I know that linked lists seem to be a fairly common problem area among beginner C programmers, most examples that I have come across abstract the sorting of a linked list to a separate function which is sadly not what I am trying to do.
The code below is my attempt to have the nodes inserted into their correct place so that once all nodes have been inserted they are already in a sorted order.
Code:
int main(int argc, char *argv[]) { struct node_t* dict_head; struct node_t* traversor; struct node_t* newnode; int list_size = 0, insert_key, search_key, delete_key, x; char insert_word[WORDLEN]; /*Opening the dictionary file provided by the command line argument */ FILE *fp; fp = fopen(argv[1], "r");
[Code]....
The problem is as follows. When you provide it with input in which the first word scanned is any other word than that which would be placed at the front of the list, it works as intended. For example.
7 world 0 ant 3 kodak 1 best 6 the 2 is
Produces ant -> best->is->kodak->best->world
However, swapping ant and world in the above input gives: world->best->is->kodak->best->world
In regards to why I have my head node set as a node without a word or a key, it was suggested that I make it so that the first node inserted is set to be the head of the list and then changed as sorting required, yet this caused only additional problems.
I was trying to write a function in C to delete a node(only from the middle) from a Singly Linked List. I wrote one but not sure if the code will work fine under all test conditions. I have tested it and shows no error so far.
Code: void deleteAt(struct node *root, int number){ while(root->link != NULL) { if(root->link->item == number) //checks if the next node is the element to be deleted { root->link = root->link->link; //points the link of the element to be deleted to the element before the element to be deleted } else root = root->link; } }
I need to delete the Nth node from a doubly linked list. I know I just cant delete it out right. I have all the goodies including a templetized node class. This is the code we're given:
template <typename T> void doublyLinkedList<T>::deleteKthElement(const int item) { }
It accepts an int, and should go to the Nth node and delete it.
I am trying to delete a node from the end of a Linked List but I have some problems. Every node has it's unique code. Here is what I do:
1. Ask the user for the unique code of the node. 2. Ask him if he wants to change the data in it or delete the whole node. 3. If he chooses to delete it, I do this:
//let's say that temp1 points to the node List *temp2 = temp1; temp1 = temp1->next; delete temp2;
i am trying to develop a doubly linked list class. I became stuck at a few of the functions as well as the main.cpp file. i have to insert a character sentence "TRICK OR TREAT" spaces included. I am stuck on the display and the listsize functions and im unsure if my insert has the head node in it. The function parameters were given to us and most of this code was given from a single linked list.
I am studying this sample code for linked list class node implementation. I am not 100% sure how this code keeps track of the head node. Here's what I know so far, and if you want to add/correct anything feel free to do so:
class Node { public: Node(); // constructor of class node without arguments Node(int, Node*); //constructor with arguments of int type and a pointer node type Node* next() const; void setNext(Node*); //member fun, returning a pointer of node type void setKey(int);
I'm trying to calculate the total price of books contained in a linked list. I've tried getTotal() function in linked list but error: no match for 'operator+=' in 'total += ptr->Node<Book>::info'| occurred. How can I access the price in the node and then calculate the total price.
Here is part of my code :
Book class class Book { protected : int id; string title; double price; string bookStatus;
